One way in which access to systems or devices can be controlled is through the use of fingerprint authentication, in which a user's fingerprint is captured by a fingerprint sensor and authenticated. However, current authentication systems are not without their problems. One such problem is that authentication systems sometimes assume that a user of the phone does not change for an amount of time after the user is authenticated. This can result in situations where the user of the phone changes, but this change is not discovered by the authentication system.